Along with editing and filming itself, color grading is one of those skills that set videos apart, if done right.
Since color grading requires a sense of art direction, a good eye for color and mastery of the editing software's elusive color control tools, some videographers opt for coating their footage with generic, one size fits all LUT's (poor substitutes for real color grading), or worse, just using the footage the way it comes out of the camera.
And you might ask: how come the footage simply doesn't come out ready from the camera, instead of those washed out tones (what we in the industry call LOG footage)
As you certainly have noticed by now, every great photographer edits and enhances their photos with post production software (like Photoshop). The images don't come out perfect straight out of the camera because the camera cannot guess how the photographer wants them to look. At most, all it can is to make a rough guess, which is what camera presets really are. And that's good enough if you're a weekend photographer, or you're just shooting your kids with your phone. If you're a pro however, that's not enough. It might land you some good images now and then, but greatness will always be out of reach. For that, you'll have a better chance using the camera's raw feature, in order to preserve the most details as possible (presets "cook" the image and destroy detail).
And the exact same thing happens in video as well. Images need to be worked and sculptured (it's photography afterall, only moving), but many videographers just lack the photographer's eye and the skill set to polish their images in post. Have a look at the video above, if you haven't done so already. If your images look more like "log" than "graded", then you're missing a crucial step in the video making process.